Fix shard counts

Half of these groups moved to the rabbitmq_web_mqtt plugin.

Author: ansd

deps/rabbitmq_mqtt/BUILD.bazel

@@ -232,7 +232,7 @@ rabbitmq_integration_suite(
         ":test_util_beam",
         ":test_event_recorder_beam",
     ],
-    shard_count = 10,
+    shard_count = 5,
     runtime_deps = [
         "//deps/rabbitmq_management_agent:erlang_app",
         "@emqtt//:erlang_app",
@@ -247,7 +247,7 @@ rabbitmq_integration_suite(
     additional_beam = [
         ":test_util_beam",
     ],
-    shard_count = 4,
+    shard_count = 2,
     runtime_deps = [
         "@emqtt//:erlang_app",
         "@gun//:erlang_app",